Relativelyfast

I have a 2000 Banshee that I purchased used 3 years ago. It has some modifications allready but I'm not sure about what is inside of the engine as I was not able to speak with the previous owner. What I have: Cool head FMF pipes +4 swingarm no key switch aftermarket brakes bigger jets k&n filters lots of billet polished parts on engine no idea what is inside of it seems a touch faster than a piped and jetted 450. a touch faster than stock raptor 700 What I think I want from reading around: Intended for sand use I kind of want to do an ebay special engine build 4mm crank (does it have to be a long rod?) ebay used dune ported cyls (will get them bored) want to run race gas what domes? new carbs what ones are best to look for on ebay? Any help on anything I need would be great, thanks.